Polyester resin compositions and processes for the preparation thereof

ABSTRACT

Polyester resin compositions each comprising a polyester resin and a silane-treated phyllosilicate, wherein the silane-treated foliated phyllosilicate is one prepared by incorporating a swellable phyllosilicate salt with organo-silane of the general formula (I): Y n SiX 4−n  (wherein n is an integer of 0 to 3; Y is an optionally substituted C 1 -C 25  hydrocarbon group; and X is a hydrolyzable group or hydroxyl, with the proviso that when n or 4−n is 2 or above, nY&#39;s or (4−n)X&#39;s may be the same or different from each other) and the maximum layer thickness of the silane-treated foliated phyllosilicate in the composition is larger than 100 Å but smaller than 2000 Å.

TECHNICAL FIELD

The present invention relates to a polyester resin compositioncomprising a polyester resin and a silane-treated foliatedphyllosilicate, and to a process for preparing the same.

BACKGROUND ART

A polyester resin such as poly(ethylene terephthalate) has been used ina lot of industrial applications, for example, as a fiber and a film,since they are excellent in thermal resistance, chemical resistance,weatherability, mechanical properties, electrical properties and thelike.

If a polyester resin composition can be prepared by dispersing asilicate, which is a silicon-containing compound having a layeredstructure, into the polyester resin in the form of a uniform layer, itis expected that mechanical properties and thermal resistance of thepolyester resin can be improved without deterioration in surfaceappearance.

As a process for preparing such a resin composition using anorgano-silane, following processes have been conventionally known. (1) Aprocess for preparing a polymer nanocomposite, wherein monomers of aresin are polymerized in the presence of layered or fibrillar particlestreated with an organometallic compound such as an organo-silane (thepamphlet of International Patent Publication No. 95/06090 (1995), thespecification of U.S. Pat. No. 5,514,734).

(2) A process for preparing a polymer nanocomposite, wherein layeredparticles treated with an organo-silane or an onium salt and a meltkneadable resin are melt kneaded with a kneading machine such as a twinscrew extruder (the pamphlet of International Patent Publication No.93/04118 (1993), the pamphlet of International Patent Publication No.93/11190 (1993)).

(3) A process for preparing a poly(arylene sulfide) composite material,comprising dissolving poly(arylene sulfide) in an organic solvent suchas N-methyl-2-pyrrolidone, then dispersing a layered silicate treatedwith an organic onium salt, an organic halogenated silane or an organicsilazane, and thereafter re-precipitating in a poor solvent such aswater (Japanese Unexamined Patent Publication No. 194851/1993).

As a process for preparing the resin composition without using theorgano-silane, following processes have been conventionally known.

(4) A process for preparing a thermoplastic polyester compositionwherein a layered inorganic filler having an interlayer charge of 0.2 to1.0 is swollen with glycols and thereafter a polyester resin ispolymerized (Japanese Unexamined Patent Publication No.26123/1995).

(5) A process for preparing a thermoplastic polyester composition,wherein an inorganic compound such as swellable fluoromica obtained byheating a mixture of talc and alkali silicofluoride in a specificproportion is swollen with glycols and thereafter a polyester resin ispolymerized (Japanese Unexamined Patent Publication Nos. 268188/1995 and73710/1996).

In the above-mentioned (1) and (2) there is disclosed an inventionrelating to a resin composite material comprising a resin matrix andlayered particles combined with an organometallic compound such as anorgano-silane and, having an average layer thickness of at most about 50Å and the maximum layer thickness of at most about 100 Å, namely, acomposite material using layered particles combined with anorgano-silane and nylon 6 as a resin matrix, for the purpose ofimproving resin's flexural modulus, flexural strength, deflectiontemperature under load and dimensional stability. But no resin compositematerial using a polyester resin as a resin matrix has been disclosed.If these processes apply to polyester resins, it is not sufficient todisperse the layered particles treated with silane and to improvemechanical properties and thermal resistance. When the process (3) isapplied for a polyester resin, a mixed solvent of phenol andtetrachloroethane, hexafluoroisopropanol and the like can be mentionedas the organic solvent. From the viewpoints of safety and health,productivity, available poor solvents and the like, such a process isnot industrially available at all and is extremely difficult to beapplied as a process for preparing a polyester resin composition.

On the other hand, Japanese Unexamined Patent Publication No.118792/1997points out that dispersing layered particles into molecules withseparating them into individual layers in a polypropylene-based resin orin a vinyl-based polymer allows the layered particles to form a laminatestructure, so that it becomes difficult for the layered particles toshow isotropic properties (Science of Clay, Vol. 30 (2), 143-147 (1990))and that when layered particles inherently having a high modulus ofelasticity are dispersed into conditions similar to unit layers, theybend and the obtained modulus of elasticity is less than inherentlyexpected.

The tensile modulus of elasticity of the composite material usinglayered particles combined with an organo-silane and nylon 6, which isdisclosed in the above-mentioned (1) and (2) available fromAllied-Signal Inc., has been improved in comparison with that of thenylon 6 resin itself. But it exhibits insufficient improvement comparedto a composite material composed of layered particles treated withammonium 11-decanoate and nylon 6.

Furthermore, the present inventors obtained a composite material bydispersing layered particles into a thermoplastic polyester resin in theform of a laminar structure similar to their unit layer (the thicknessof the unit layer is about 10 Å) and evaluated its flexural modulus,flexural strength, deflection temperature under load and dimensionalstability. It has been found that the effects are insufficient thoughthey have been improved in comparison with materials in which suchconventional particles are contained, in the form of laminated andflocculated states, in a thermoplastic polyester resin by means of anextrusion melt mixing or the like.

Moreover, the present inventors have attempted to prepare athermoplastic polyester resin composition in accordance with theconventional methods using no organo-silane, namely, the methods of (4)and (5), but could not obtain desired dispersing state, layer thicknessand physical properties. Namely, a small amount of a swellablefluoromica could not improve modulus of elasticity or deflectiontemperature at all, and it was found out that a layer thickness or adispersing state of the swellable fluoromica in the composition are thesame as those of the aggregated structure of the swellable fluoromicabefore mixing by transmission electron microscope observation andsmall-angle X-ray diffraction measurement.

As mentioned above, the present situation is that techniques in which apolyester resin composition having excellent physical properties isobtained by safely, completely, uniformly and finely dispersinginorganic substances into a thermoplastic polyester resin have not beenprovided yet.

Accordingly, even if a layered silicate is dispersed in a state similarto forming a unit layer, wherein the average layer thickness is at mostabout 50 Å and the maximum layer thickness is at most about 100 Å, oreven if layered silicate is incorporated in a conventional state whereinit remains laminated or flocculated, it is difficult to obtain polyesterresin compositions sufficiently improved in mechanical properties,deflection temperature under load and dimension stability.

DISCLOSURE OF THE INVENTION

The object of the present invention is to solve the above-mentionedconventional problems and to provide a polyester resin compositionhaving improved flexural modulus of elasticity, flexural strength,deflection temperature under load and dimensional stability, which cangive molded articles with excellent appearance and to provide a processfor preparing the same by exfoliating inorganic compounds into laminarshaving suitable thickness which can exhibit an effect of improvingphysical properties and dispersing the inorganic compounds as manyindividual layers with thickness in nanomerter orders.

Namely, the present invention relates to

(1) a polyester resin composition comprising a thermoplastic polyesterresin and a silane-treated foliated phyllosilicate, wherein thesilane-treated foliated phyllosilicate is prepared by introducing anorgano-silane represented by the following general formula (I):

Y_(n)SiX_(4−n)  (I)

wherein n denotes an integer of 0 to 3, Y denotes a hydrocarbon grouphaving 1 to 25 carbon atoms which may have a substituent, X denotes ahydrolyzable group or a hydroxyl group, n units of Y or (4−n) units of Xmay, respectively, be the same or different if n or (4−n) is at least 2,into a swellable phyllosilicate

and wherein the maximum layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is more than 100 Å andat most 2000 Å,

(2) the polyester resin composition of the above-mentioned (1), whereinthe maximum layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is 200 Å to 1800 Å,

(3) the polyester resin composition of the above-mentioned (1), whereinthe maximum layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is 300 Å to 1500 Å,

(4) the polyester resin composition of the above-mentioned (1), (2) or(3), wherein the average layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is at least 20 Å andat most 500 Å,

(5) the polyester resin composition of the above-mentioned (1), (2) or(3), wherein the average layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is more than 50 Å andat most 300 Å,

(6) the polyester resin composition of the above-mentioned (1), (2),(3), (4) or (5), wherein the dispersing particle number [N] of thesilane-treated foliated phyllosilicate particles present in a 100 μm²area of the polyester resin composition is at least 30 based on unitproportion,

(7) the polyester resin composition of the above-mentioned (1), (2),(3), (4), (5) or (6), wherein an average aspect ratio (layerlength/layer thickness ratio) of the silane-treated foliatedphyllosilicate in the polyester resin composition is 10 to 300,

(8) the polyester resin composition of the above-mentioned (1), (2),(3), (4) or (5), wherein a proportion ([R100] value) of the number ofsilane-treated foliated phyllosilicate having layer thickness greaterthan 100 Å to the total number of the silane-treated foliatedphyllosilicate is at least 10%,

(9) the polyester resin composition of the above-mentioned (1), (2),(3), (4) or (5), wherein the [R(100)] value is at least 30%,

(10) the polyester resin composition of the above-mentioned (1), (2),(3), (4) or (5), wherein the [R(100)] value is at least 50%,

(11) the polyester resin composition of the above-mentioned (8), (9) or(10), wherein a proportion ([R200] value) of the number ofsilane-treated foliated phyllosilicates having layer thickness greaterthan 200 Å to the total number of the silane-treated foliatedphyllosilicate is at least 0.3×[R100],

(12) the polyester resin composition of the above-mentioned (8), (9) or(10), wherein the [R200] value is at least 0.7×[R100],

(13) the polyester resin composition of the above-mentioned (11) or(12), wherein a proportion ([R300] value) of the number ofsilane-treated foliated phyllosilicates having layer thicknesses greaterthan 300 Å to the total number of the silane-treated foliatedphyllosilicate is at least 0.4×[R200],

(14) the polyester resin composition of the above-mentioned (11) or(12), wherein the [R300] value is at least 0.8×[R200],

(15) a process for preparing a polyester resin composition comprising athermoplastic resin and a silane-treated foliated phyllosilicate, whichcomprises

(A) a step of preparing a silane-treated foliated phyllosilicate byintroducing an organo-silane represented by the general formula (I):

Y_(n)SiX_(4−n)  (I)

wherein n denotes an integer of 0 to 3, Y denotes a hydrocarbon grouphaving 1 to 25 carbon atoms which may have a substituent, X denotes ahydrolyzable group or a hydroxyl group, n units of Y or (4−n) units of Xmay, respectively, be the same or different if n or (4−n) is at least 2,to a swellable phyllosilicate,

(B) a step of preparing a dispersion system by mixing the silane-treatedfoliated phyllosilicate and glycols,

(C) a step of preparing a mixture by adding the dispersion system to amolten polyester unit and/or polyester with a low molecular weight, and

(D) a step of increasing a molecular weight of the polyester unit and/orthe polyester with a low molecular weight in the above mixture bycondensation polymerization,

(16) the process for preparing a polyester resin composition of theabove-mentioned (15), wherein, in the step (A), the silane-treatedfoliated phyllosilicate is obtained by adding the organo-silane afterenlarging a basal spacing of the swellable phyllosilicate in adispersion medium, and therby a basal spacing of the silane-treatedfoliated phyllosilicate becomes larger than the initial basal spacing ofthe swellable phyllosilicate by the organo-silane introduced,

(17) the process for preparing a polyester resin composition of theabove-mentioned (15) or (16), wherein an basal spacing of thesilane-treated foliated phyllosilicate dispersing in the dispersionsystem obtained in the step (B) is at least three times larger than theinitial basal spacing of the swellable phyllosilicate,

(18) the process for preparing a polyester resin composition of theabove-mentioned (15), (16) or (17), wherein a logarithmic viscosity ofthe polyester unit and/or the polyester with a low molecular weight isat least 0.001 dl/g and less than 0.4 dl/g, and

(19) the process for preparing a polyester resin composition of theabove-mentioned (15), (16), (17) or (18), wherein the polyester unitand/or the polyester with a low molecular weight is obtained bydepolymerizing a polyester resin material with glycols.

BEST MODE FOR CARRYING OUT THE INVENTION

The polyester resin composition of the present invention is a polyesterresin composition comprising a thermoplastic polyester resin and asilane-treated foliated phyllosilicate, wherein the silane-treatedfoliated phyllosilicate is prepared by introducing an organo-silanerepresented by the following general formula (I):

Y_(n)SiX_(4−n)  (I)

wherein n denotes an integer of 0 to 3, Y denotes a hydrocarbon grouphaving 1 to 25 carbon atoms which may have a substituent, X denotes ahydrolyzable group or a hydroxyl group, n units of Y or (4−n) units of Xmay, respectively, be the same or different if n or (4−n) is at least 2,to a swellable phyllosilicate, and wherein the maximum layer thicknessof the silane-treated foliated phyllosilicate in the polyester resincompound is more than 100 Å and at most 2000 Å.

There is no particular limitation for the thermoplastic polyester resinof the present invention, but it includes known homopolymers and/orcopolymers which are synthesized from one or at least two kinds ofaromatic dicarboxylic acids or alkyl esters thereof and one or at leasttwo kinds of glycols. Examples of the thermoplastic polyester resins arepoly(ethylene terephthalate), poly(propylene terephthalate),poly(butylene terephthalate), poly(hexamethylene terephthalate),poly(cyclohexane-1,4-dimethyl terephthalate), poly(neopentylterephthalate), poly(ethylene isophthalate), poly(ethylene naphthalate),poly(butylene naphthalate), poly(hexamethylene naphthalate) and thelike, and polyester copolymers thereof. Among these thermoplasticpolyester resins, poly(ethylene terephthalate) and poly(butyleneterephthalate) can be preferably used. These thermoplastic polyesterresins may be used solely or in a combination use of two or more thereofhaving different composition or component and/or viscosity.

The swellable phyllosilicate is substantially formed of a tetrahedralsheet of silicon oxide and octahedral sheet of metal hydroxide, andexamples thereof are smectite group clay minerals, swellable mica,kaolin group clay minerals and the like.

The smectite group clay minerals are represented by the general formula(II):

X_(0.2-0.6)Y₂₋₃Z₄O₁₀(OH)₂ .nH₂O  (11)

wherein X denotes at least one kind selected from the group consistingof K, Na, ½Ca and ½Mg, Y denotes at least one kind selected from thegroup consisting of Mg, Fe, Mn, Ni, Zn, Li, Al and Cr, and Z denotes atleast one kind selected from the group consisting of Si and Al. They maybe either a natural product or a chemically synthesized product.

Although H₂O denotes a water molecule bonding to an interlayer ion, nremarkably changes depending upon an interlayer ion and a relativehumidity.

Examples of the smectite group clay minerals are montmorillonite,beidellite, nontronite, saponite, iron saponite, hectorite, sauconite,stevensite, bentonite and the like, or their substituted products, theirderivatives and mixtures thereof.

The smectite group clay minerals have basal spacing of approximately 10to 17 Å in their initial flocculated state. The smectite group clayminerals in their flocculated states have thickness of 1000 Å to1,000,000 Å.

The swellable mica is represented by the general formula (III):

X₀₅₋1.0Y₂₋₃(Z₄O₁₀)(F,OH)₂  (III)

wherein X denotes at least one kind selected from the group consistingof Li, Na, K, Rb, Ca, Ba and Sr, Y denotes at least one kind selectedfrom the group consisting of Mg, Fe, Ni, Mn, Al and Li, and Z denotes atleast one kind selected from the group consisting of Si, Ge, Al, Fe andB. They may be either a natural product or a chemically synthesizedproduct. The swellable mica has a property that it swells in water, apolar solvent compatible with water in arbitrary proportion or a mixedsolvent containing water and the polar solvent. Examples thereof arelithium taeniolite, sodium taeniolite, lithium type tetrasilicate mica,sodium type tetrasilicate mica and the like, or their substitutedproducts, their derivatives or mixtures thereof. In the presentinvention the following compounds corresponding to the vermiculites alsocan be employed as a kind of the swellable micas.

The swellable mica has basal spacing of approximately 10 to 17 Å intheir initial flocculated states. The swellable mica in theirflocculated state has thickness of approximately 1,000 Å to 1,000,000 Å.

The clays corresponding to the vermiculites include the trioctahedraltype and the dioctahedral type, and the clays represented by the generalformula (IV):

(Mg, Fe, Al)₂₋₃(Si_(4−x)Al_(x))O₁₀(OH)₂.(M⁺, M²⁺ _(½))_(x) .nH₂O  (IV)

wherein M denotes an exchangeable cation of alkali or alkaline earthmetal such as Na and Mg, x denotes 0.6 to 0.9 and n denotes 3.5 to 5.

The clays corresponding to the vermiculites have basal spacing ofapproximately 10 to 17 Å in their initial flocculated state. The clayscorresponding to the vermiculites in their flocculated state havethickness of approximately 1,000 Å to 5,000,000 Å.

As the kaolin group clay minerals, examples are a natural or chemicallysynthesized kaolinite, dickllite, halloysite and the like, or theirsubstituted products, their derivatives or mixtures thereof.

The synthesized kaolin group clay minerals can be prepared, for example,by the following method. For example, synthesized kaolinite isprecipitated in a method wherein colloidal silica and alumina sol aremixed in a kaolinite composition ratio to form a starting material,which is then subjected to hydrothermal treatment by setting aconcentration of the starting material high and treating at 150 to 300°C. (S. Tomura et al. Clays Clay Miner., 33,200 (1985)). Moreover, thesynthesized hallosite can be obtained by leaching feldspar with aSoxhlet extractor or the like (W. E. Parham, Clays Clear Miner., 17, 13(1969)).

As the swellable phyllosilicate, the above-mentioned ones can be usedsolely or in a combination of two or more thereof. Among these,montmorillonite, bentonite, hectorite, saponite, swellable mica havingsodium ions between layers, and kaolinite are preferable, and especiallymontmorillonite, bentonite, swellable mica having sodium ions betweenlayers and kaolinite are preferable from the viewpoints ofdispersibility in a thermoplastic resin, physical property improvingeffect to the obtained thermoplastic resin composition, and ease to get.

The above-mentioned swellable phyllosilicate is used solely or in acombination use of two or more thereof. Although the swellablephyllosilicates preferably have a crystal structure with a high purityin which each layer is superposed on another layer regularly in thec-axis direction, there can also be used so-called mixed-layer clayminerals having an irregular crystal cycle and plural kinds of crystalstructures.

The organo-silane which is introduced into the above-mentioned swellablephyllosilicates are an organo-silane represented by the general formula(I):

Y_(n)SiX_(4−n)  (I)

In the general formula (I), n denotes an integer of 0 to 3, Y is ahydrocarbon group having 1 to 25 carbon atoms which may have asubstituent.

In the case where the hydrocarbon group having 1 to 25 carbon atoms hasa substituent, examples thereof are a group combined with an ester bond,a group combined with an ether bond, an epoxy group, an amino group, acarboxyl group, a group having a carbonyl group on a terminal thereof,an amide group, a mercapto group, a group combined with a sulfonyl bond,a group combined with a sulfinyl bond, a nitro group, a nitroso group, anitrile group, a halogen atom, a hydroxyl group and the like. Thehydrocarbon group may be substituted with one of these substituents orat least two substituents.

X denotes a hydrolyzable group and/or a hydroxyl group. Examples of thehydrolyzable group are at least one selected from the group consistingof an alkoxy group, an alkenyloxy group, a ketoxime group, an acyloxygroup, an amino group, an aminoxy group, an amide group and a halogenatom.

In the general formula (I), when n or (4−n) is at least 2, n units of Yor (4−n) units of X may be the same or different.

In this specification, the hydrocarbon groups are linear or branched(that is, having a side chain), saturated or unsaturated, monovalent orpolyvalent, aliphatic, aromatic or alicyclic hydrocarbon groups.Examples thereof are an alkyl group, an alkylene group, an alkenylgroup, an alkenylene group, an alkynyl group, an alkynylene group, aphenyl group, a phenylene group, a naphtyl group, a naphtylene group, acycloalkyl group, a cycloalkylene group and the like.

In the general formula (I), examples in which Y is a hydrocarbon grouphaving 1 to 25 carbon atoms are a group having a linear long chain alkylgroup such as decyltrimethoxysilane, a group having a lower alkyl groupsuch as methyltrimethoxysilane, a group having a unsaturated hydrocarbongroup such as 2-hexenyltrimethoxysilane, a group having an alkyl groupwith a side chain such as 2-ethylhexyltrimethoxysilane, a group having aphenyl group such as phenyltriethoxysilane, a group having a naphthylgroup such as 3-β-naphthylpropyltrimethoxysilane, a group having anaralkyl group such as p-vinylbenzyltrimethoxysilane, and the like.Examples in which Y is a group having a vinyl group among groups having1 to 25 carbon atoms are vinyltrimethoxysilane, vinyltrichlorosilane,vinyltriacetoxysilane and the like. Examples in which Y is a grouphaving a group substituted with a group combined with an ester bond areγ-methacryloxypropyltrimethoxysilane and the like. Examples in which Yis a group having a group substituted with a group combined with anether group are γ-polyoxyethylenepropyltrimethoxysilane,2-ethoxyethyltrimethoxysilane and the like. Examples in which Y is agroup substituted with an epoxy group areγ-glycidoxypropyltrimethoxysilane and the like. Examples in which Y is agroup substituted with an amino group are γ-aminopropyltrimethoxysilane,γ-(2-aminoethyl)aminopropyltrimethoxysilane,γ-anilinopropyltrimethoxysilane and the like. Examples in which Y is agroup substituted with a group having a carbonyl group on a terminalthereof are γ-ureidopropyltrimethoxysilane and the like. Examples inwhich Y is a group substituted with a mercapto group areγ-mercaptopropyltrimethoxysilane and the like. Examples in which Y is agroup substituted with a halogen atom are γ-chloropropyltriethoxysilaneand the like. Examples in which Y is a group substituted with a groupcombined with a sulfonyl bond are γ-phenylsulfonylpropyltrimethoxysilaneand the like. Examples in which Y is a group substituted with a groupcombined with a sulfinyl bond are γ-phenylsulfinylpropyltrimethoxysilaneand the like. Examples in which Y is a group substituted with a nitrogroup are γ-nitropropyltriethoxysilane and the like. Examples in which Yis a group substituted with a nitroso group areγ-nitrosopropyltriethoxysilane and the like. Examples in which Y is agroup substituted with a nitrile group are γ-cyanoethyltriethoxysilane,γ-cyanopropyltriethoxysilane and the like. Examples in which Y is agroup substituted with a carboxyl group areγ-(4-carboxyphenyl)propyltriethoxysilane and the like.

In the present invention, other than the above-mentioned compound, anorgano-silane in which Y is a group having a hydroxyl group can beemployed. Examples thereof areN,N-di(2-hydroxyethyl)amino-3-propyltriethoxysilane and the like.

A hydroxyl group can be a form of a silanol group (SiOH).

Among the above-mentioned organo-silane, the compound can be selected tosufficiently increase its reactivity with a swellable phyllosilicate andits compatibility or dispersibility with an obtained silane-treatedfoliated phyllosilicate and a thermoplastic polyester resin or adispersion medium such as glycols, which is used in a step of adding adispersion medium in a preferred process for preparing the polyesterresin composition of the present invention, which is mentioned later.However, in the general formula (I), the compound is preferable, inwhich X is at least one selected from the group consisting of an alkoxygroup, a chlorine atom and a hydroxyl group, and Y is a group selectedfrom the group consisting of a group having an amino group as asubstituent, a group having an ester group, a group having an ethergroup, a group having an epoxy group and a group having an amide group.Examples of the organo-silane are γ-aminopropyltrimethoxysilane,γ-aminopropyltriethoxysilane, γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-(2-aminoethyl)aminopropyltriethoxysilane,γ-methacryloxypropyltrimethoxysilane,γ-methacryloxypropyltrichlorosilane,γ-poly(oxyethylenepropyltrimethoxysilane), 2-ethoxyethyltriethoxysilane,γ-glycidoxypropyltrimethoxysilane, and γ-glycidoxypropyltriethoxysilane.

Substituted products or derivatives of the organo-silane can be alsoemployed. These organo-silane may be used solely or in a combination useof two or more thereof.

The silane-treated foliated phyllosilicate used in the present inventioncan be obtained, for example, by a process comprising expanding a basalspacing of a swellable phyllosilicate in a dispersion medium andthereafter adding the above-mentioned organo-silane.

As the dispersion medium, examples are water, a polar solvent compatiblewith water in an arbitrary concentration, and mixed solvent of water andthe polar solvent.

Examples of the polar solvent are alcohols such as methanol, ethanol andisopropanol, glycols such as ethylene glycol, propylene glycol and1,4-butanediol, ketones such as acetone and methyl ethyl ketone, etherssuch as diethyl ether and tetrahydrofuran, amide compounds such asdimethylformamide, and other solvents such as dimethyl sulfoxide and2-pyrrolidone, and the like. These polar solvents may be used solely orin a combination use of two or more thereof.

The basal spacing of the swellable phyllosilicate in the dispersionmedium can be expanded by stirring and dispersing the swellablephyllosilicate in the dispersion medium. The basal spacing afterexpansion is at least three times, preferably at least five times,larger than the initial basal spacing of the swellable phyllosilicate.There is not any upper limit in the basal spacing after expansion. Whenthe basal spacing is expanded as much as ten times, since the swellablephyllosilicate exists substantially in the form of unit layer, there isno need for expanding the basal spacing more than ten times.

The initial basal spacing of the swellable phyllosilicate means a basalspacing in flocculated state in which unit layers are laminated witheach other before the basal spacing is expanded in the dispersionmedium. It is usually about 7 to 17 Å as mentioned above, though itvaries depending upon types of the swellable phyllosilicate.

The basal spacing can be determined by a small angle X-ray diffractionmethod (SAXS) and the like. Namely, a basal spacing can be calculated bymeasuring a diffraction peak angle of a dispersion system comprising adispersion medium and a swellable phyllosilicate with SAXS, andsubstituting it in the Bragg's formula.

As a method for efficiently expanding the basal spacing of the swellablephyllosilicate, examples thereof are a method of stirring at leastthousands rpm and a method of applying physical external forces asmentioned below.

The external forces can be applied by using a conventional pulverizingmethod of fillers. Examples of the conventional method for pulverizingfillers are a method using hard particles. In this method, the layersare separated from each other by mixing and stirring hard particles, aswellable phyllosilicate and an arbitrary solvent, and then by expandinga basal spacing of the swellable phyllosilicate according to thephysical collision of the hard particles and the swellablephyllosilicate. Hard particles conventionally used are beads forpulverizing fillers. For example, glass beads, zirconia beads or thelike are employed. These beads for pulverization are selected from theviewpoint of hardness of the swellable phyllosilicate or the material ofa stirrer. Therefore, they are not restricted to the glass beads orzirconia beads. The particle size of the beads is also determined inview of the size of the swellable phyllosilicate and the like and is notalways limited. But it is preferably 0.1 to 0.6 mm in diameter. There isno particular limitation for the solvent used here, but theabove-mentioned dispersion medium is preferable.

After expanding the basal spacing of the swellable phyllosilicate toseparate the layers as mentioned above, the above-mentionedorgano-silane is added and stirred. A silane cray composite can beobtained by introducing the organo-silane to the surface of theswellable phyllosilicate having expanded basal spacing.

In a method using a dispersion medium, an organo-silane can beintroduced by adding the organo-silane to a dispersion system containinga swellable phyllosilicate having an expanded basal spacing and adispersion medium. When the organo-silane is intended to be introducedmore efficiently, a rotation rate in stirring is set to at least 1000rpm, preferably 1500 rpm, more preferably 2000 rpm, or a shear rate ofat least 500 (l/s), preferably at least 1000 (l/s), more preferably atleast 1500 (l/s) is applied by using a wet mill or the like. The upperlimit of the rotation rate is about 25,000 rpm and that of shear rate isabout 500,000 (l/s). Stirring at larger value than the upper limit orapplying a shear rate greater than the upper limit tends to no longerimprove effects any more. There is no need of stirring at greater valuesthan those upper limits, therefore.

In the method using a physical external force, the organo-silane can beintroduced by applying a physical external force to a swellablephyllosilicate (for example, with wet pulverization) and concurrentlyadding an organo-silane thereto.

Alternatively, an organo-silane can also be introduced to a swellablephyllosilicate by adding a swellable phyllosilicate having a basalspacing expanded with a physical external force into a dispersion mediumand thereafter adding the organo-silane thereto in the same manner as inthe method using the above-mentioned dispersion medium.

The reaction of a hydroxyl group on the surface of the swellablephyllosilicate with a hydrolyzable group or a hydroxyl group of anorgano-silane (X in the formula (I)) can introduce the organo-silane tothe swellable phyllosilicate. Although the reaction between theswellable phyllosilicate and the organo-silane can proceed sufficientlyat a room temperature, the reaction system may be heated if necessary.The maximum temperature in heating can be arbitrarily set as long as itis lower than the decomposition temperature of the organo-silane to beused and is lower than the boiling point of the dispersion medium.

In the present invention, “introducing an organo-silane to a swellablephyllosilicate” means reacting and combining a hydrolyzable group and/ora hydroxyl group of the organo-silane with a hydroxyl group of aswellable phyllosilicate having an expanded basal spacing, and therebymaking an organo-silane present on surface and interlayer spaces of theswellable phyllosilicate.

Moreover, when the introduced organo-silane has a reactive functionalgroup such as a hydroxyl group, a carboxyl group, an amino group, anepoxy group, a vinyl group or the like, it can be further reacted byadding a compound reacting with the reactive functional group of theorgano-silane. By the second reaction, it is possible to extend afunctional group chain length of the organo-silane introduced to theswellable phyllosilicate or to change its polarity. The compound addedin the second reaction is not limited to an organo-silane; arbitrarycompounds can be used in accordance to objects. Examples of thesecompounds are a compound containing an epoxy group, a compoundcontaining an amino group, a compound containing a carboxyl group, acompound containing an acid anhydride group and a compound containing ahydroxyl group.

The reaction can proceed sufficiently at a room temperature, it may beheated if necessary. The maximum temperature in heating can bearbitrarily set as long as it is lower than the decompositiontemperature of the used organo-silane and is lower than the boilingpoint of the dispersion medium.

An amount of the organo-silane can be adjusted in order to increasecompatibility with a silane-treated foliated phyllosilicate and glycolsand a polyester resin, and dispersibility of the silane-treated foliatedphyllosilicate. If necessary, plural types of organo-silane havingdifferent types of a functional group can be used together. The amountof the organo-silane can not always be limited using a value, but it ispreferably 0.1 to 200 parts, more preferably 0.2 to 160 parts, andparticularly preferably 0.3 to 120 parts based on 100 parts by weight(hereinafter referred to as “parts”) of a swellable phyllosilicate. Whenthe amount of the organo-silane is less than 0.1 part, a silane-treatedfoliated phyllosilicate tends not to be dispersed finely enough in thepolyester resin composition. When it exceeds 200 parts, the effects donot change.

The basal spacing of the silane-treated foliated phyllosilicate obtainedin the above-mentioned manner can be expanded in comparison with theinitial basal spacing of the swellable phyllosilicate by the presence ofthe introduced organo-silane. For example, the swellable phyllosilicatedispersed in a dispersion medium and having a basal spacing returns tothe state where layers are flocculated together again, when theorgano-silane is not introduced and the dispersion medium is removed.According to the present invention, since a basal spacing is expandedand then an organo-silane is introduced, a silane-treated foliatedphyllosilicate obtained after removal of the dispersion medium can existin a state where layers do not flocculate together and the basal spacingare still expanded. The silane-treated foliated phyllosilicate has anexpanded basal spacing expanded at least 1.3 times, preferably at least1.5 times, more preferably at least 1.7 times, especially preferably atleast 2.0 wider than the initial basal spacing of the swellablephyllosilicate. There is no particular limitation for the upper limit,but even if the basal spacing is expanded 5 times wider, the effects areno longer improved.

Thus, the introduction of the organo-silane provides the effect ofcontrolling flocculation of particles of the silane-treated foliatedphyllosilicate. And the expansion of the basal spacing can increase thecompatibility of the silane-treated foliated phyllosilicate with theglycol compound and, as a result, the dispersibility of thesilane-treated foliated phyllosilicate in the polyester resin in thedispersion system preparation step as the step (B) in the preparationprocess of the present invention.

Although the introduction of the organo-silane is confirmed by variousmethods, the following is a concrete example thereof.

First, an organo-silane merely adsorbed to the silane-treated foliatedphyllosilicate is sufficiently washed away with an organic solvent suchas tetrahydrofuran and chloroform. The silane-treated foliatedphyllosilicate after washing is ground into powder with mortar or thelike and thereafter is sufficiently dried. The resulting powder issufficiently mixed with a matrix material such as powdery potassiumbromide (KBr) in a predetermined amount and formed into a pellet bypressing. Absorption bands derived from the organo-silane introduced inthe silane-treated foliated phyllosilicate is then measured by theFourier transfer infrared spectroscopy (FT-IR) in a transmission mode orthe like. When more accurate measurement is required or when the amountof the organo-silane introduced is small, it is preferable that thesufficiently dried powdery organo-silane composite is directly measuredby the diffusion reflection method (DRIFT).

Furthermore, the silane-treated foliated phyllosilicate having a basalspacing and expanded wider than the initial basal spacing of theswellable phyllosilicate can be confirmed by various methods. A concretemethod is as follows.

A basal spacing of a silane-treated foliated phyllosilicate can bemeasured using the small-angle X-ray diffraction method (SAXS) or thelike after washing away an organo-silane merely adsorbed to thesilane-treated foliated phyllosilicate with an organic solvent in thesame manner as mentioned above and thereafter drying the resultant. Inthis method, a value of the diffraction peak derived from the (001)plane of the powdery silane-treated foliated phyllosilicate is measuredby using the SAXS and then the value is substituted to the Bragg'sformula to calculate a basal spacing. A basal spacing of the swellablephyllosilicate is calculated in the same manner. Comparison of thesebasal spacings can confirm that the basal spacing is expanded.

As mentioned above, after washing with an organic solvent, a functionalgroup derived from the organo-silane is observed with FT-IR or the like.And the formation of the silane-treated foliated phyllosilicate can beconfirmed by measuring that a basal spacing is expanded wider than theswellable phyllosilicate using SAXS or the like.

As mentioned above, the formation of the silane-treated foliatedphyllosilicate can be confirmed by confirming both the introduction ofthe organo-silane and the expansion of the basal spacing. Thus,according to the present invention, the introduction of theorgano-silane and the expansion of the basal spacing can increasecompatibility between the silane-treated foliated phyllosilicate and thepolyester resin or the glycol compound.

In the polyester resin composition of the present invention, an amountof the silane-treated foliated phyllosilicate is adjusted to 0.1 to 50parts, preferably 0.2 to 45 parts, more preferably 0.3 to 40 partsparticularly preferably 0.4 to 35 parts, and especially preferably 0.5to 30 parts based on 100 parts of the polyester resin. When the amountof the silane-treated foliated phyllosilicate is less than 0.1 part,mechanical properties, deflection temperature under load and dimensionalstability are not sufficiently improved. When it exceeds 50 parts, thereis a tendency that appearance of molded articles, fluidity duringmolding and the like become worse.

The ash content of the polyester resin composition derived from thesilane-treated foliated phyllosilicate is adjusted to typically 0.1 to30% by weight (hereinafter referred to as “%”), preferably 0.2 to 28%,more preferably 0.3 to 25%, particulary preferably 0.4 to 23%,especially preferably 0.5 to 20%. When the ash content is less than0.1%, mechanical properties, deflection temperature under load anddimensional stability are not sufficiently improved. When it exceeds30%, there is a tendency that appearance of molded articles, fluidityduring molding and the like becomes worse.

A structure of the silane-treated foliated phyllosilicate dispersed inthe polyester resin composition of the present invention is quitedifferent from the μm-sized flocculated structure possessed by theswellable phyllosilicate before incorporation, in which a lot of layersare laminated. Namely, by using a silane-treated foliated phyllosilicatein which an organo-silane having compatibility with a matrix has beenintroduced and a basal spacing has been expanded wider than that of theinitial swellable phyllosilicate, its layers are further exfoliated fromeach other. As a result, the silane-treated foliated phyllosilicate isdispersed in the polyester resin composition in a state of very fine,independent and laminars, and the number thereof remarkably increases incomparison with the swellable phyllosilicate as the raw material. Such adispersing condition of the laminar can be expressed by a maximum layerthickness, an average layer thickness, the number of dispersingparticles [N], an aspect ratio (layer length/layer thickness ratio) anda parameter mentioned later of the silane-treated foliatedphyllosilicate.

First, the lower limit of the maximum layer thickness of thesilane-treated foliated phyllosilicate in the polyester resincomposition of the present invention is more than 100 Å, preferably atleast 150 Å, more preferably at least 200 Å, particularly preferably atleast 300 Å, especially preferably at least 400 Å. When the thickness ofthe maximum layer dispersing in the polyester resin composition is atmost 100 Å, there is a tendency that mechanical properties, deflectiontemperature under load and dimensional stability of the molded articlesobtained from the polyester resin composition of the present inventionare not sufficiently improved. Moreover, the upper limit thereof is 2000Å, preferably 1800 Å, more preferably 1500 Å, particularly preferably1200 Å, especially preferably 1000 Å. When the upper limit of the layerthickness of the silane-treated foliated phyllosilicate is more than2000 Å, the surface of a molded article obtained from the polyesterresin composition of the present invention is sometimes lost.

The lower limit of the average layer thickness of the silane-treatedfoliated phyllosilicate in the polyester resin composition of thepresent invention is at least 20 Å, preferably at least 30 Å, morepreferably at least 50 Å, particularly preferably at least 60 Å,especially preferably at least 70 Å. The upper limit of the averagelayer thickness of the silane-treated foliated phyllosilicate is at most500 Å, preferably at most 450 Å, more preferably at most 400 Å,particularly preferably at most 350 Å, especially preferably at most 300Å. When the average thickness layer is in the above-mentioned range,mechanical properties, deflection temperature under load and dimensionstability can be improved without losing an appearance of the moldedarticle obtained from the polyester resin composition of the presentinvention.

Defining the number average of layer length/layer thickness ratio of thesilane-treated foliated phyllosilicate dispersing in the polyester resinas an average aspect ratio, the average aspect ratio of thesilane-treated foliated phyllosilicate in the polyester resincomposition of the present invention is 10 to 300, preferably 15 to 300,more preferably 20 to 300. When the average aspect ratio of thesilane-treated foliated phyllosilicate is less than 10, there may be acase that modulus of elasticity, deflection temperature under load ofthe polyester resin composition of the present invention are notsufficiently improved. Since the effects are no longer improved even ifthe average aspect ratio exceeds 300, there is no need for setting theaverage aspect ratio more than 300.

Defining the number of the dispersing particles based on unit weightproportion of the swellable phyllosilicate in a 100 μm² area of thepolyester resin composition as the value [N], the [N] value of thesilane-treated foliated phyllosilicate in the polyester resincomposition of the present invention is at least 30, preferably at least45, more preferably at least 60. There is no particular limitation forthe upper limit, but when the [N] value exceeds about 1,000, the effectis no longer improved. Therefore, there is no need for setting the [N]value more than 1,000.

The above-mentioned parameter of the polyester resin composition of thepresent invention can be expressed as follows. Namely, when a proportionof the number of the silane-treated foliated phyllosilicate having alayer thickness of more than 100 Å and not more than the upper limit ofthe above-mentioned maximum layer thickness among the silane-treatedfoliated phyllosilicate dispersing in the polyester resin composition isdefined as [R100], the [R100] value in the polyester resin compositionof the present invention is at least 10%, preferably at least 20%, morepreferably at least 30%, particularly preferably at least 40%,especially preferably at least 50%. When the [R100] value is at least10%, mechanical properties, deflection temperature under load anddimensional stability of the molded articles obtained from the polyesterresin composition of the present invention can be further improvedwithout losing an appearance of the molded article. Although there is noparticular limitation for the upper limit, when the [RL100] value is atleast 80%, the effect is no longer improved.

In the polyester resin composition of the present invention, when aproportion of the number of the silane-treated foliated phyllosilicatehaving a layer thickness of at least 200 Å and not more than the upperlimit of the maximum layer thickness among the silane-treated foliatedphyllosilicate dispersing in the polyester resin composition is definedas [R200], the [R200] value in the polyester resin composition of thepresent invention is at least 0.3×[R100]%, preferably at least0.4×[100]%, more preferably 0.5×[R100]%, particularly preferably atleast 0.6×[100]%, especially preferably at least 0.7×[R100]%. When the[R200] value is at least 0.3×[R100]%, mechanical properties, deflectiontemperature under load and dimensional stability of the polyester resincomposition are further improved. Although there is no particularlimitation for the upper limit, when the [R200] value is at least0.85×[R100]%, the effect is no longer improved.

In the polyester resin composition of the present invention, when aproportion of the number of the silane-treated foliated phyllosilicatehaving a layer thickness of at least 300 Å and not more than theabove-mentioned upper-limit among the silane-treated foliatedphyllosilicate dispersing in the polyester resin composition is definedas [R300], the [R300] value in the polyester resin composition of thepresent invention is at least 0.4×[R200]%, preferably at least0.5×[R200]%, more preferably at least 0.6×[R200]%, particularlypreferably at least 0.7×[R200]%, especially preferably at least0.8×[R200]%. When the [R300] value is at least 0.4×[R100]%, mechanicalproperties, deflection temperature under load and dimensional stabilityof the polyester resin composition are further improved. Although thereis no particular upper limit, when the [R300] value is at least0.95×[R200] %, the effect is no longer improved.

If the silane-treated foliated phyllosilicate is dispersed in a state ofthe above-mentioned layer thickness, the polyester resin composition canmaintain high modulus since the composite gives isotropic properties tothe polyester resin composition and the composite itself is notdistorted. Since the silane-treated foliated phyllosilicate having sucha layer thickness is contained in the polyester resin composition in theabove-mentioned amount, mechanical properties, deflection temperatureunder load and dimensional stability of molded articles are sufficientlyimproved without losing an appearance thereof.

In this specification, the layer thickness can be determined fromimages, taken by using a microscope or the like, of films obtained byhot press molding or drawing after heating and melting the polyesterresin composition of the present invention, or thin articles obtained byinjection molding of the molten resin.

Namely, it is assumed that a film prepared according to theabove-mentioned method or a thin plate-like test piece obtained byinjection molding having a thickness approximately 0.5 to 2 mm is placedon an X-Y plane. The layer thickness can be determined by cutting thefilm or the plate along an X-Z or Y-Z plane into a thin layer andobserving the thin layer at high magnifications as high as approximatelyat least forty thousand to one hundred thousand. Instead of theabove-mentioned film or plate, the layer thickness can also bedetermined by cutting, perpendicularly to the drawing axis, a fibrilarmaterial obtained by monoaxially drawing into a thin layer and observingit with a transmission electron microscope. The layer thickness can bequalified, for example, by forming a picture image using an imageprocessing device from the image obtained by the transmission electronmicroscope and processing the picture image with a computer.Alternatively, in the case where the transmission electron microscopehas a sufficiently high magnification, for example, one hundred thousandtimes, it can also be determined by measuring with a ruler or the likewithout using the image processing devices. Therefore, in the presentinvention, a layer thickness of the silane-treated foliatedphyllosilicate can be qualified, for example, by using a photographshowing the dispersion state of the silane-treated foliatedphyllosilicate obtained by taking a photograph of the polyester resincomposition of the present invention with a transmission electronmicroscope.

In this specification, the maximum layer thickness means the maximum oflayer thickness of the silane-treated foliated phyllosilicate detectedby choosing an arbitrary region, in which at least 100 dispersing layersof the silane-treated foliated phyllosilicate is contained in atransmission electron microscope image obtained by the above-mentionedmethod or the like. The average layer thickness means a value obtainedby a number averaging the layer thickness of the silane-treated foliatedphyllosilicate measured in the area as mentioned above.

A proportion of the number of the silica clay composite having a layerthickness of at least 100 Å, [R100], can be obtained by choosing anarbitrary region containing at least 100 of dispersing layers of thesilane-treated foliated phyllosilicate in the same manner as themeasurement of the average layer thickness and measuring a layerthickness of every dispersing layer.

The [N] value can be obtained, for example, by the following method.Namely, the [N] value can be obtained in such a manner that a polyesterresin composition is cut into an ultrathin section of about 50 μm to 100μm thickness and the number of particles of the silane-treated foliatedphyllosilicate present in an arbitrary 100 μm² region in an image of theultrathin section taken by means of TEM or the like is divided by theweight ratio of the used swellable phyllosilicate. Alternatively, the[N] value may also be defined by a value obtained in such a manner thatthe number of particles present in an arbitrary region (its area ispreviously measured), in which at least 100 of the particles arepresent, is chosen in the TEM image, and divided by the weight ratio ofthe used swellable phyllosilicate and the resulting number is convertedto the number for a 100 μm² area. Accordingly, the [N] value can bequalified by using a TEM photograph of a polyester resin composition, orthe like.

The thermoplastic polyester resin composition of the present inventioncontaining a silane-treated foliated phyllosilicate, which is dispersedin a laminar form in the dispersing state, can be prepared by, in adispersion system containing a previously prepared silane-treatedfoliated phyllosilicate and polymerizable monomers forming a polyesterresin, polymerizing the polymerizable monomer, and preferably preparedby the following method.

A process for preparing a polyester resin composition comprising athermoplastic polyester resin and a silane-treated foliatedphyllosilicate of the present invention comprises a preparation step (A)of the silane-treated foliated phyllosilicate, a preparation step (B) ofthe dispersion system (B), a preparation step (C) of the mixture and amolecular weight increasing step (D), as mentioned above.

The present invention is explained below in the above order of thesteps.

First, in the step (A) in the present invention, a silane-treatedfoliated phyllosilicate is prepared by introducing an organo-silanecomposition represented by the general formula (I):

Y_(n)SiX_(4−n)  (I)

wherein n denotes an integer of 0 to 3, Y denotes a hydrocarbon grouphaving 1 to 25 carbon atoms which may have a substituent, X denotes ahydrolyzable group or a hydroxyl group, n units of Y or (4−n) units of Xmay, respectively, be the same or different if n or (4−n) is at least 2,to the above-mentioned swellable phyllosilicate.

As the step (B) of the process for preparing the polyester resincomposition of the present invention, the above-mentioned silane-treatedfoliated phyllosilicate and glycols are mixed to prepare a glycoldispersion system.

As the glycols used in the present invention, examples are aliphaticglycols such as ethylene glycol, propylene glycol, butylene glycol,hexylene glycol and neopentyl glycol, alicyclic glycols such as1,4-cyclohexane dimethanol, and aromatic glycols such as1,4-phenylenedioxy dimethanol. Substituted products and derivativesthereof can be also employed. Cyclic esters such as ε-caprolactone canbe also employed. These may be used solely or in a combination use oftwo or more thereof. Moreover, at least one selected from, for example,long chain diols such as poly(ethylene glycol) and poly(tetramethyleneglycol) and, for example, alkylene oxide adduct polymers of bisphenolssuch as ethylene oxide-adduct polymers of bisphenol-A and the like canbe mixed in such a small amount that the modulus of elasticity of thepolyester resin is not remarkably decreased.

As for a mixing ratio of the glycols and the silane-treated foliatedphyllosilicate, there is no requirement except that the amount of thesilane-treated foliated phyllosilicate is 0.5 to 50 parts based on 100parts of the glycols. It is preferably 0.5 to 40 parts, more preferably0.5 to 30 parts from the viewpoint of dispersibility of thesilane-treated foliated phyllosilicate.

There is no particular limitation for a method of the above-mentioneddispersion system preparing step (B). Examples thereof include: whenglycols are used as a dispersion medium in the silane-treated foliatedphyllosilicate preparing step (A) a method in which a system containingthe dispersion medium and the silane-treated foliated phyllosilicate isused as a glycol dispersion system (this method is referred to as adirect method; in this case, the silane-treated foliated phyllosilicatepreparing step (A) also serves as the dispersion system preparing step(B)); a method in which to a system containing a dispersion medium and asilane-treated foliated phyllosilicate obtained in the preparation ofthe silane-treated foliated phyllosilicate is mixed desired glycols andthen, if necessary, the dispersion medium is removed to use glycols as adispersion medium (this method is referred to as a substitution method);or a method in which a silane-treated foliated phyllosilicate previouslyprepared and glycols are sufficiently mixed. From the viewpoint ofdispersibility of the silane-treated foliated phyllosilicate, the directmethod and the substitution method are preferable.

In order to mix efficiently, a rotation rate in stirring is set to be atleast 500 rpm or a shear rate of at least 300 (l/s) is applied. Theupper limit of the rotation rate is 25,000 rpm and that of the shearrate is 500,000 (l/s). Since stirring at values over the upper limittends to remain the same effect, there is no need for stirring at thevalue over the upper limits.

In the silane-treated foliated phyllosilicate contained in the glycoldispersion system obtained in the above-mentioned manner, the initiallamination/flocculation structure, which the swellable phyllosilicatepossess, disappears and the silane-treated foliated phyllosilicate isled to a so-called swollen state in which spacing between layers areexpanded. As an index for expressing the swollen state, a basal spacingcan be used. That is, a basal spacing of the silane-treated foliatedphyllosilicate in the glycol dispersion system obtained in thedispersion system preparing step (B) is at least three times, preferablyat least four times, more preferably at least five times larger than theinitial basal spacing of the swellable phyllosilicate. When the basalspacing is less than three times, the silane-treated foliatedphyllosilicate tends not to finely disperse efficiently in a polyesterresin composition obtained according to the preparing process of thepresent invention.

There is no particular limitation for the upper limit, but even if thebasal spacing is expanded at least ten times, the effect is no longerimproved.

Next, as the step (C) of the process for preparing the polyester resincomposition of the present invention can be carried out a step in whichthe dispersion system is added to a molten polyester unit and/or apolyester having a low polymerization degree to obtain a mixture.

In the present invention, the “polyester unit” means a condensate formedfrom one molecule of an aromatic dicarboxylic acid or its ester formablederivative and one molecule of glycols or its ester formable derivative.The “polyester having a low polymerization degree” means a condensatecomprising an aromatic dicarboxylic acid or its ester formablederivative and glycols or its ester formable derivative. Moreover, thepolyester unit and the polyester having a low polymerization degree areones having a molecular weight corresponding to such melt viscosity thatthe dispersion system containing the silane-treated foliatedphyllosilicate can be dispersed in a molten state sufficiently anduniformly.

From the viewpoint of uniform dispersibility of the glycol dispersionsystem, the polyester unit and/or the polyester having a lowpolymerization degree have a logarithmic viscosity of less than 0.4(dl/g), preferably less than 0.38 (dl/g), more preferably less than 0.35(dl/g), particularly preferably less than 0.33 (dl/g) and especiallypreferably less than 0.30 (dl/g). There is no particular limitation forthe lower limit, but it is preferably 0.001 (dl/g).

Examples of the aromatic dicarboxylic acids are terephthalic acid,isophthalic acid, orthophthalic acid, 2,5-naphthalene dicarboxylic acid,4,4′-biphenyl dicarboxylic acid, 4,4′-diphenyl ether dicarboxylic acid,4,4′-diphenylmethane dicarboxylic acid, 4,4′-diphenylsulfonedicarboxylic acid, 4,4′-diphenylisopropylidene dicarboxylic acid and thelike, their substituted product, their derivative, oxyacids such asp-oxybenzoic acid and p-hydroxyethoxybenzoic acid, and their esterformable derivative. These monomers may be used solely or in acombination use of two or more thereof.

At least one aliphatic dicarboxylic acid such as adipic acid, azelaicacid, dodecane dicarboxylic acid and sebacic acid can be used with thesearomatic dicarboxylic acids in a small amount that characteristics ofthe obtained polyester resin composition are not lost.

As the glycols, the same one as those used in the dispersion systempreparing step (B) can be used. At least one compound listed as anexample can be used.

There is no particular limitation for a method for obtaining thepolyester unit and/or the polyester having a low polymerization degree.Examples are conventional methods such as a method in which an aromaticdicarboxylic acid is esterified with glycols, a method in which anaromatic dicarboxylic acid alkyl ester and glycols are transesterified,and the like.

In addition to a method in which the compounds are obtained bycondensation reacting an aromatic dicarboxylic acid or its esterformable derivative with glycols or its ester formable derivative,example thereof is a method in which the target compounds are obtainedby depolymerizing a part of or the whole of a polyester resin withglycols. Namely, examples are a method in which a mixture of a polyesterresin and glycols as a raw material is heated, and depolymerized withstirring at about 150° C. to about a melting point of the polyesterresin, a method in which a polyester resin as a raw material ispreviously melt, depolymerization is carried out by adding glycolsthereto under stirring, and the like.

A catalyst needed in the reaction for obtaining the above polyester unitand/or the polyester having a low polymerization degree is atransesterification catalyst, and at least one kind of metal oxides,carbonates, acetates, alcoholates and the like can be used. In themethod for obtaining the target compounds by depolymerization of apolyester resin, although a catalyst required for the reaction isusually contained previously in the polyester resin as the startingmaterial, the above-mentioned transesterification catalyst may beadditionally used if necessary.

As the glycols used in the depolymerization of the polyester resin,there can be used at least one kind of those previously mentioned as theglycols used in the dispersion system preparing step.

In this case, when a resin component contained in the polyester resincomposition obtained by the preparing process of the present inventionis formed into a copolymerized polyester resin obtained bycopolymerizing a polyester resin as a raw material with the otherglycols, glycols having a structure different from that of the glycolsused in the dispersion system preparing step (B) is used for thedepolymerization of the polyester resin as a raw material.

There is no particular limitation for a method of the mixture preparingstep (C) in the preparation process of the present invention. Example isa method in which to the polyester unit and/or the polyester having alow polymerization degree obtained by the above-mentioned method in amolten state is continuously added a glycol dispersion system. Theaddition can be carried out at an arbitrary timing during the reactionas long as a logarithmic viscosity of the polyester unit and/or thepolyester having a low polymerization degree is less than 0.4 (dl/g),preferably less than 0.38 (dl/g), more preferably less than 0.35 (dl/g),particularly preferably less than 0.33 (dl/g). When the logarithmicviscosity is at least 0.4 (dl/g), there is a tendency that thesilane-treated foliated phyllosilicate is insufficiently finelydispersed.

An amount of the glycol dispersion system added to 100 parts of thepolyester unit and/or the polyester having a low polymerization degreein a molten state is required to be 1 to 500 parts. But it is preferably2 to 400 parts, more preferably 5 to 300 parts.

In the step (C) of the preparation process of the present invention, atleast one compound selected from the group consisting of an aromaticdicarboxylic acid or its ester formable derivative and glycols or itsester formable derivative may be added to the polyester unit and/or thepolyester having a low polymerization degree in a molten state, as longas a logarithmic viscosity is in the above-mentioned range.

Next, as the step (D) of the process for preparing the polyester resincomposition of the present invention, the molecular weight increasingstep is carried out, in which the polyester unit and/or the polyesterhaving a low polymerization degree present in the mixture obtained inthe previous step (C) by a condensation polymerization reaction.

There is no particular limitation for a method for increasing molecularweight and it can be carried out by conventional polymerization methodsof polyester resins.

As these methods, examples are a method in which a mixture obtained inthe above-mentioned mixture preparing step (C), containing thesilane-treated foliated phyllosilicate, the glycols and the polyesterunit and/or the polyester having a low polymerization degree in a moltenstate is stirred, the excess glycols are removed from the system andthereafter a pressure of the system is reduced to carry out meltcondensation polymerization, a method in which the system is cooled tosolidify at an arbitrary timing from before or after the beginning ofthe melt condensation polymerization to the completion ofpolymerization, the resultant is pulverized, preliminarily crystallized,dried, and thereafter heated to 150° C. to a melting point to carry outa solid phase polymerization, and the like.

When the other glycols is copolymerized with the polyester resincomponent, the target product is obtained by adding and mixing desiredglycols at an arbitrary timing during the melt condensationpolymerization, and thereafter carrying out the melt condensationpolymerization reaction.

As a catalyst required for the above-mentioned condensationpolymerization reaction, there can be used at least one kind of metaloxides, carbonates, acetates, alcoholates and the like.

A molecular weight of the polyester resin whose molecular weight hasbeen increased in the step (D) is in such a range that a logarithmicviscosity measured at 25° C. using a phenol/tetrachloroethane (5/5weight ratio) mixed solvent is 0.4 to 2.0 (dl/g), preferably 0.42 to 1.9(dl/g), more preferably 0.45 to 1.8 (dl/g). When the logarithmicviscosity is less than 0.4 (dl/g), mechanical properties tend to be low.When the logarithmic viscosity is larger than 2.0 (dl/g), moldingfluidity tends to be low because of high melt viscosity.

The reason why the polyester resin composition of the present inventionis excellent in mechanical properties, heat resistance, dimensionstability, surface appearance and moldability is that the silane-treatedfoliated phyllosilicate is dispersed in the resin in the form of manyfine laminar particles, and a maximum layer thickness, an average layerthickness, the number of dispersing particles, an average aspect ratioand the like of the silane-treated foliated phyllosilicate are in theabove-mentioned ranges.

The dispersing state of the silane-treated foliated phyllosilicate canbe controlled by at least one step selected from the group consisting ofthe silane-treated foliated phyllosilicate preparing step (A), thedispersion system preparing step (B) and the mixture preparing step (C).

That is, for example, if a stirring force or a shearing force isconstant during dispersing the swellable phyllosilicate in the step (A),swollen and exfoliated states of the swellable phyllosilicate varydepending upon the type of the dispersion medium, and in the case ofusing a plurality of dispersion mediums, mixing proportion and mixingorder thereof. For example, when montmorillonite is used as theswellable phyllosilicate, montmorillonite is swollen and exfoliated intostates similar to unit layers. Therefore, when it is reacted with anorgano-silane having a group having high polarity such as an aminogroup, a mercapto group and a nitrile group at such states, a system canbe prepared, in which a silane-treated foliated phyllosilicate having athickness close to a unit layer thickness is dispersed. On the otherand, when a mixed solvent of water and a polar solvent such as ethanol,tetrahydrofuran (THF), methyl ethyl ketone (MEK) or N-methylpyrrolidone(NMP) is used as a dispersion medium or when montmorillonite isdispersed in the polar solvent and thereafter water is added, it isexfoliated and finely divided into a state wherein about several toabout one hundred and several tens flakes of unit layers are laminated.When it is reacted with an organo-silane in the state, a system can beprepared in which a silane-treated foliated phyllosilicate having athickness corresponding to about several to about one hundred andseveral tens unit layers is dispersed. The dispersing state of thesilane-treated foliated phyllosilicate can be controlled by conductingthe steps (B), (C) and (D) in order to maintain the state.

In the substitution method in the step (B) (a method in which thedispersion medium used in the preparation of the silane-treated foliatedphyllosilicate is substituted with desired glycols), the dispersingstate of the silane-treated foliated phyllosilicate in a glycoldispersion system changes depending upon the type of the added glycols,and in the case of using a plurality of glycols, mixing proportion andmixing order thereof. For example, when, for example, ethylene glycol or1,4-butanediol is added to a water matrix system containing asilane-treated foliated phyllosilicate in a unit layer state tosubstitute the water, about several to about several tens laminars ofthe silane-treated foliated phyllosilicate in the unit layer state canflocculate and be laminated. The dispersing state can be controlled byconducting the steps of (C) and (D) of the preparing process of thepresent invention in order to maintain the state.

In the step (C), the dispersing state varies depending upon a type and amolecular weight of the polyester unit and/or the polyester having a lowpolymerization degree to be mixed with a glycol dispersion system. Forexample, in the case where the organo-silane has an amino group,especially bishydroxyethyl terephthalate (BHET) or bishydroxybutylterephthalate (BHBT) among all polyester units is mixed with the glycoldispersion system, a layer thickness of the silane-treated foliatedphyllosilicate does not almost change before and after mixing andpolymerization can be carried out with maintaining the dispersing state.On the other hand, continuous addition of a glycol dispersion system toa polyester having a low polymerization degree with a logarithmicviscosity of approximately 0.05 to 0.20 (dl/g) can form a laminatehaving about several to about several tens layers. The dispersing statecan be controlled by conducting the step (D) in order to maintain thestate.

To the polyester resin composition of the present invention can be addedpolybutadiene, a copolymer of butadiene and styrene, an acrylic rubber,an ionomer, a copolymer of ethylene and propylene, a copolymer ofethylene, propylene and diene, a natural rubber, a chlorinated butylrubber, a homopolymer of α-olefin, a copolymer of at least two α-olefins(including any copolymers such as random, block and graft; mixturesthereof are also permitted), or impact modifiers such as an olefinicelastomer. These may be modified with an acid compound such as maleicanhydride or an epoxy compound such as glycidyl methacrylate.

Unless properties such as mechanical properties and moldability arelost, there can be used thermoplastic resins or unsaturated polyesterresins such as a copolymer of poly(ester ether), a polycarbonate resin,a polyestercarbonate resin, a liquid crystal polyester resin, apolyolefinic resin, a polyamide resin, a styrenic resin reinforced witha rubber polymer, a poly(phenylene ether) resin, a polyacetal resin, apolysulfone resin, a polyarylate resin, a polyimide and apolyetherimide, thermosetting resins such as epoxy resin and aphenolnovolac resin. These may be used solely or in a combination use oftwo or more thereof.

Moreover, according to an object, there can be added additives such as apigment, a dye, a heat stabilizer, an antioxidant, a ultravioletabsorbers, an optical stabilizer, a lubricant, a plasticizer, a flameretardant and an antistatic agents. The polyester resin compositionobtained by the present invention can be formed by an injection moldingor a hot press molding, and blow molding is also applicable. Moldedarticles obtained from the polyester resin composition of the presentinvention are excellent in appearance, mechanical properties, heatdeflection resistance and the like. Therefore, they can be suitably usedfor automobile parts, household electrical appliances, housewares,wrapping materials, and other general industrial materials.

The present invention is explained in further detail below referring toexamples, but the invention is not limited thereto.

First, major raw materials used in Examples and Comparative Examples areshown all together below. Unless otherwise specified, raw materials werenot purified.

(Swellable Phyllosilicate)

Smectite group clay minerals: Natural montmorillonite produced inYamagata Prefecture. (Basal spacing=1.3 nm)

Swellable mica prepared in the following manner was used.

Synthesis of swellable mica: 28.2 g of swellable mica was obtained bymixing 25.4 g of talc and 4.7 g of sodium silicofluoride and heating at800° C. (Basal spacing=1.2 nm)

(Organo-silane)

γ-(2-Aminoethyl)aminopropyltrimethoxysilane: A-1120 available from NihonUnicar. Co., Ltd.

γ-Glycidoxypropyltrimethoxysilane: A-187 available from Nihon UnicarCo., Ltd.

γ-(Polyoxyethylene)propyltrimethoxysilane: A-1230 available from NihonUnicar Co., Ltd.

(Glycols)

Ethylene glycol: monoethylene glycol available from Nippon Shokubai Co.,Ltd. (hereinafter referred to as “EG”)

1,4-Butanediol: 1,4-butanediol available from Tosoh Corp. (heneinafterreferred to as “1,4-BD”)

(Thermoplastic Polyesters)

PET: PBK2 available from Kanebo, Ltd. (poly(ethylene terephthalate), alogarithmic viscosity (ηinh)=0.63 (dl/g)) (hereinafter referred to as“PET”)

PBT: PBT120 available from Kanebo, Ltd. (poly(butylene terephthalate), alogarithmic viscosity (ηinh)=0.82 (dl/g)) (hereinafter referred to as“PBT”)

Next, evaluation methods in Examples and Comparative Examples are shownall together below.

(FT-IR)

A washing operation was repeated three times, which comprises adding 1.0g of a silane-treated foliated phyllosilicate to 50 ml oftetrahydrofuran (THF), stirring for 15 minutes to wash and remove anadsorbed organo-silane and thereafter conducting centrifugation toremove a supernatant. After washing, about 1 mg of the fully driedsilane-treated foliated phyllosilicate and about 200 mg of KBr powderwere sufficiently mixed with a mortar, and thereafter a KBr disk formeasurement was prepared with a bench press machine. The disk wasmeasured in a transmission mode using an infrared spectrometer (8100Mmanufactured by Shimadzu Corp.) As a detector was used an MCT detector.A resolution and the number of scanning were set 4 cm⁻¹ and 100 times,respectively.

(Logarithmic Viscosity)

After the obtained polyester resin composition was dried at 140° C. for4 hours, about 100 mg of the composition was weighted accurately todissolve it at 120° C. by mixing with 20 ml of aphenol/1,1,2,2-tetrachloroethane (1/1 weight ratio) mixed solvent. Usingan Ubbellohde viscometer, a viscosity of a solution was measured at ameasuring temperature of 25° C. in the case of using PET or at ameasuring temperature of 20° C. in the case of using PBT using anautomatic viscosity measuring machine (Viscotimer manufactured by LaudaAG). A logarithmic viscosity (ηinh) was calculated from the followingformula:

ηinh={ln ( t/t ₀)}/C

wherein t denotes a value of falling time of a solution, t0 denotes avalue of falling time of a mixed solvent only, and C denotes aconcentration (g/dl).

(Measurement of basal spacing by small-angle X-ray Diffraction Method(SAXS))

Using an X-ray generator (RU-200B manufactured by Rigaku Denki KabushikiKaisha), a basal spacing was measure under the following measuringconditions: target CuKα beam, Ni filter, voltage 40 kV, electric current300 mA, scanning angle 2θ=0.2 to 16.0°, and a step angle=0.02°.

A basal spacing was calculated by substituting a small-angle X-ray peakangle into the Bragg's formula. When it was difficult to identify asmall-angle X-ray peak angle, it was considered that layers were fullyexfoliated and crystallinity was completely lost or that since the peakangle value was at most about 0.8° the identification was difficult.Thus, the evaluation result of a basal spacing was expressed as >100 Å.

(Transmission Electron Microscope (TEM))

A film of a polyester resin composition (film thickness: 100 to 300 μm)was prepared under conditions of a temperature of 250 to 270° C. and agauge pressure of 5 to 15 kg/cm² using a hot press machine.

Using a microtome, a thin slice for observation sample (50 to 100 μm inthickness) was cut out along a direction perpendicular to the filmsurface. Using a transmission electron microscope (JEM-1200EXmanufactured by JEOL Ltd.), a dispersing state of the silane-treatedfoliated phyllosilicate was evaluated at an accelerating voltage of 80kV and a magnification of 40,000 to 100,000.

Measurement was conducted by choosing a region in a TEM photograph inwhich at least 100 dispersing particles were present and thereaftermanually measuring the number of dispersing particles [(N] value), layerthickness and layer length with a scale or, if necessary, processing thephotograph with an image analyzer PIAS III manufactured by InterquestCo.

The maximum layer thickness was defined as the maximum value among layerthickness of every silane-treated foliated phyllosilicate. The averagelayer thickness was defined as the number average value of layerthickness of every silane clay.

The [N] value was determined as follows. First, in a TEM image, thenumber of silane-treated foliated phyllosilicate particles present in achosen region is counted. On the other hand, ash content of thepolyester resin composition derived from the silane-treated foliatedphyllosilicate is measured. The [N] value is obtained by dividing thenumber of the particles by the ash content to convert the result into avalue for a 100 μm² area.

The average aspect ratio was defined as the number average of layerlength to layer thickness ratio of every silane-treated foliatedphyllosilicate.

[100] is defined as a proportion of particles having a layer thicknessof at least 100 Å among the observed dispersing particles. [R200] isdefined as a proportion of particles having a layer thickness of atleast 200 Å among the observed dispersing particles. [R300] is definedas a proportion of particles having a layer thickness of at least 300 Åamong the observed dispersing particles.

When the dispersing particles are so large that observation with TEM isinadequate, the [N] value is obtained in the same manner as previouslymentioned using an optical microscope (an optical microscope BH-2manufactured by Olympus Optical Co., Ltd.). A sample was melted at 250to 270° C. by using a hot stage THM600 manufactured by LINKAM and the astate of dispersing particles was measured in the molten state ifnecessary.

A layer thickness of dispersing particles, which are not dispersed intoplates, is defined as a shorter diameter thereof. An aspect ratio isdefined as a value of (longer diameter)/(shorter diameter). A “longerdiameter” of a particle means a longer side of an imaginary rectangle,which has the smallest area of the rectangle circumscribing the particlein a microscope image or the like. In addition, a shorter diameter meansa shorter side of the smallest rectangle.

(Ash Content)

An ash content of the polyester resin composition derived from asilane-treated foliated phyllosilicate is measured according to JIS K7052.

(Deflection Temperature Under Load)

After drying a polyester resin composition at 140° C. for 5 hours, atest piece having dimensions of about 10×100×6 mm is prepared byinjection molding at a resin temperature of 250 to 280° C., a gaugepressure of about 10 MPa and an injection rate of bout 50% using aninjection molding machine with a mold clamping force of 75 t (IS-75Emanufactured by Toshiba Machine Co., Ltd.). A deflection temperatureunder load of the obtained test piece is measured according to ASTMD-648.

(Flexural Property)

Flexural strength and flexural modulus of a test piece prepared in thesame manner as that in the case of the deflection temperature under loadare measured according to ASTM D-790.

(Warpage)

After drying a polyester resin composition (140° C., 5 hours), a flatplate-like test piece having a dimension of about 120×120×1 mm isprepared by injection molding under conditions of a die temperature of50° C., a resin temperature of 250 to 280° C., a gauge pressure of about10 MPa and an injection rate of bout 50% using an injection moldingmachine with a mold clamping force of 75 t (IS-75E manufactured byToshiba Machine Co., Ltd.) The flat plate-like test piece was placed ona plane. One of the four corners of the test piece was pushed againstthe plane, and the largest value among the distances from the plane toeach of the three remaining corners is measured with vernier calipers orthe like. Each of the four corners was pushed alternately and an averageof the obtained warpage values is calculated.

(Heat Shrinkage Ratio)

A flat plate-like test piece having a dimension of about 120×120×2 mmwas injection molded under the same conditions as previously mentioned.The flat plate-like test piece was annealed at 150° C. for 3 hours.Dimensions in the MD direction and the TD direction of the test pieceafter annealing are measured and a heat shrinkage ratio is calculated byusing the following formula:

Heat shrinkage ratio={(actual dimension of die)−(dimension of test pieceafter annealing)}×100/(actual dimension of die)(%)

(Coefficient of Linear Expansion)

JIS 1 dumbbell-shaped test pieces having about 3mm thickness are used,which are prepared under the same conditions as those in the case ofdeflection temperature under load.

A center portion of the dumbbell-shaped test piece is cut out into asize of about 7 mm×7 mm. After the test piece is held at 20° C. for 5minutes with SSC-5200 and TMA-120C manufactured by Seiko ElectronicsComponents Ltd., it is heated in the range of 20 to 150° C. at a heatingrate of 5° C./minute.

A coefficient of linear expansion in the range of 30 to 120° C. wascalculated.

(Roughness at Center Line)

By using the dumbbell-shaped test piece, roughness at a center line ismeasured with a surface roughness meter surfcom 1500A manufactured byTokyo Seimitsu Co., Ltd.

(Surface Appearance of Molded Article)

By using a test piece prepared in the same manner as that in the case ofdeflection temperature under load, brilliance and color tone thereof arevisibly observed to evaluate according to the following criteria:

∘: There is brilliance and there is no unevenness in color tone.

Δ: It is not transparent or there is a unevenness in color tone.

X: It is not transparent and there is a unevenness in color tone. clEXAMPLES 1 TO 10

silane-treated Foliated Phyllosilicate Preparing Step (A) (Preparationof an Aqueous Dispersion System Containing a Silane-treated FoliatedPhyllosilicate and Water)

(Silane-Treated Foliated Phyllosilicates a to d)

A swellable phyllosilicate was dispersed into ion-exchanged water understirring at 5000 rpm for 3 minutes using a high-speed stirrer. Afterthat, aqueous dispersion system comprising a silane-treated foliatedphyllosilicate and water was obtained by dropping the organo-silaneshown in Table 1 with a simple pipette and stirring. These aredesignated as water/silane-treated foliated phyllosilicates a to d.

Among the organo-silane, A1120(γ-(2-aminoethyl)aminopropyltrimethoxysilane) was directly as it was,A187 (γ-glycidoxypropyltrimethoxysilane) was used after hydrolysis withethanol/water mixed solvent whose pH was previously adjusted to 5.0, andA1230 (γ-polyoxyethylenepropyltrimethoxysilane) was used afterhydrolysis with water whose pH was previously adjusted to 3.0 withhydrochloric acid.

The silane-treated foliated phyllosilicate was identified by measuring,with SAXS, a basal spacing of a sample obtained by separating solidsfrom a dispersion system, drying and pulverizing the solids, and bymeasuring absorption bands of a functional group derived from anorgano-silane obtained by washing a silane-treated foliatedphyllosilicate with THF by means of FT-IR.

Kinds, amounts, and measurements of the above-mentioned raw materialsare shown in Table 1.

TABLE 1 silane-treated foliated mont phyllosilicate deionized morilloswellable basal water nite mica A1120 A187 A1230 stirring IR absorptionspacing (g) (g) (g) (g) (g) (g) conditions band (Å) water/silane- 5200150 15 6000 rpm primary amino 25 treated foliated 2 hrs group, secondaryphyllosilicate a amino group, ethylene group water/silane- 4500 150 1520000S⁻¹ epoxy group, 19 treated foliated 3 hrs ether group,phyllosilicate b methylene group water/silane- 4500 150 15 20000S⁻¹ether group, 22 treated foliated 3 hrs ethylene group phyllosilicate cwater/silane- 3500 150 30 30000S⁻¹ primary amino 17 treated foliated 3hrs group, secondary phyllosilicate d amino group, ethylene group A1120γ-(2-aminoethyl)aminopropyltrimethoxysilane A187γ-glycidoxypropyltrimethoxysilane A1230γ-(polyoxyethylene)propyltrimethoxysilane

Dispersion System Preparing Step (B) (Preparation of Dispersion SystemComprising a Silane-Treated Foliated Phyllosilicate and Glycols or BHET)

Dispersion systems (containing a trace of water) comprising asilane-treated foliated phyllosilic ate and EG, 1,4-BD or BHET wereprepared by sufficiently mixing a dispersion system containing asilane-treated foliated phyllosilicate shown in Table 2 and water, andEG (ethylene glycol), 1,4-BD (1,4-butanediol) or BHET (bishydroxyethylterephthalate), stirring at a temperature of approximately 100 to 130°C. for about 3 hours, and removing water by reducing pressure withstirring for about 1 hour. Dispersion systems containing thesilane-treated foliated phyllosilicates a to d and EG are designated asEG- a to d, dispersion system containing a silane-treated foliatedphyllosilicate a and 1,4-BD is designated as BD-a, and dispersionsystems containing silane-treated foliated phyllosilicates a to d andBHET are designated as BHET-a to d.

Small-angle X-ray diffraction measurement (SAXS) of the obtaineddispersion systems was carried out to measure basal spacings of thesilane-treated foliated phyllosilicates contained in the dispersionsystems.

Table 2 shows the used water/silane-treated foliated phyllosilicates ato d, EG, 1,4-BD, BHET and measurement of basal spacings.

TABLE 2 basal spacing of water/silane-treated foliated silane-treatedfoliated dispersion phyllosilicate glycols BHET phyllosilicate in mediuma (g) b (g) c (g) d (g) EG (g) 1.4-BD (g) (g) dispersion medium EG - a4200 1700 >100 EG - b 3000 1250 78 EG - c 3000 1250 >100 EG - d 24001250 71 BD - a 4200 1700 >100 BHET - a 1200 2500 >100 BHET - b 30002500 >100 BHET - c 3000 2500 >100 BHET - d 3000 2500 >100

A polyester resin composition was prepared by using PET, a dispersionsystem EG- a, EG and a stabilizer as in the following manner.

Mixture Preparing Step (C)

A polymerization apparatus equipped with a distillation tube was chargedwith 2000 g of PET, 600 g of EG, 6.0 g of a hindered phenol typestabilizer (Adekastab AO60 available from Asahi Denka Kogyo K. K.,hereinafter referred to as “AO60”). The mixture was stirred for about 1hour and 30 minutes under dry nitrogen stream at a reaction temperatureof 180 to 240° C. with distilling the excess EG to depolymerize PET.After the depolymerization, a sampled mixture had a logarithmicviscosity of 0.14 (dl/g). The product obtained by the depolymerizationwas kept at 230 to 250° C., and 1400 g of the dispersion system EG-a wascontinuously added thereto under dry nitrogen stream with stirringadequately (100 to 140 rpm) by means of an H-shaped stirring blade. Theadding rate of the dispersion system was about 2000 g/hour.

Molecular Weight Increasing Step (D)

After removing most (at least 70%) of the EG contained in the dispersionsystem added in the dispersion medium adding step with heating thereaction system to 280° C., the pressure of the system was reduced (0.5to 5.0 torr) to melt condensation polymerization.

The polyester resin compositions obtained in the above-mentioned mannerwere evaluated. The results are shown in Tables 3 and 4.

EXAMPLES 2 TO 9

Polyester resin compositions were prepared in the following manner usingthe dispersion systems (EG- a to d) containing the silane-treatedfoliated phyllosilicates a to d and EG, the dispersion systems(dispersion systems BHET -a to d) containing the silane-treated foliatedphyllosilicates a to d and BHET, which were obtained in thesilane-treated foliated phyllosilicate preparing step (A) and thedispersion system preparing step (B), and using EG, a stabilizer and apolymerization initiator.

Mixture Preparing Step (C)

A polymerization apparatus equipped with a distillation tube was chargedwith a dispersion system (in a molten state at 120 to 140° C.)containing a silane-treated foliated phyllosilicate and BHET, astabilizer AO60, and 0.36 g of antimony trioxide (Sb₂O₃, hereinafterreferred to as Sb₂O₃) as a polymerization initiator. Subsequently, themixture was heated and kept at 230 to 250° C. under dry nitrogen stream,and a dispersion system containing a silane-treated foliatedphyllosilicate and EG was continuously added with stirring the reactionsystem adequately (100 to 140 rpm) by means of an H-shaped stirringblade. The adding rate of the dispersion system was about 2000 g/hour.

Molecular Weight Increasing Step (D)

After removing most (at least 70%) of the EG contained in the dispersionsystem added in the dispersion medium adding step with heating thereaction system to 280° C., the pressure of the system was reduced (0.5to 5.0 torr) to polymerize in melt condensation.

The used raw materials were shown in Table 3.

The polyester resin compositions obtained in the above-mentioned mannerwere evaluated. The results are shown in Tables 3 and 4.

EXAMPLE 10

A polyester resin composition was prepared in the following manner usingPBT, the dispersion system BD-a, 1,4-BD and a stabilizer.

Mixture Preparing Step (C)

A polymerization apparatus equipped with a distillation tube was chargedwith 2000 g of PBT, 600 g of 1,4-BD, 6.0 g of A)60 to depolymerize PBT,and the excess 1,4-BD was distilled off by stirring under dry nitrogenstream at a reaction temperature of 200 to 240° C. for about 1 hour. Asampled mixture had a logarithmic viscosity of 0.17 (dl/g).

The molten product obtained by the depolymerization was kept at 230 to240° C., and 1400 g of the dispersion system BD-a was continuously addedthereto with stirring adequately (100 to 140 rpm) by means of anH-shaped stirring blade. The adding rate of the dispersion system wasabout 2000 g/hour.

Molecular Weight Increasing Step (D)

After removing most (at least 70%) of the 1,4-BD contained in thedispersion system added in the dispersion medium adding step withheating the reaction system to 270° C., the pressure of the system wasreduced (0.5 to 5.0 torr) to polymerize in melt condensation.

The polyester resin compositions obtained in the above-mentioned mannerwere evaluated. The results are shown in Tables 3 and 4.

TABLE 3 example 1 2 3 4 5 6 7 8 9 10 amount of silane-treated parts by4.8 4.8 4.8 4.8 4.8 10.0 4.8 4.8 4.8 4.8 foliated phyllosilicate (*1)weight glycol dispersion kind EG-a EG-a EG-a EG-a EG-a EG-a EG-b EG-cEG-d BD-a medium g 1600 1130 810 480 250 1700 810 810 810 1600 BHETdispersion kind BHET-a BHET-a BHET-a BHET-a BHET-a BHET-b BHET-c BHET-dmedium g 690 1150 1610 2120 2500 690 690 690 polyester unit PET (*2) g2000 1480 1130 780 400 110 1480 1480 1480 or polymer EG 600 450 340 240120 33 450 450 450 having PBT (*3) g 2000 a low 1.4-BD 600polymerization degree stabilizer g 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.0 6.06.0 glycol EG g 600 500 400 400 300 400 500 500 500 1.4-BD 600logarithmic viscosity at dl/g 0.14 0.13 0.11 0.09 0.09 0.12 0.13 0.130.13 0.17 adding dispersion medium logarithmic viscosity of dl/g 0.630.63 0.62 0.62 0.63 0.61 0.63 0.63 0.63 0.63 polyester resin compositionash content % by 4.3 4.4 4.3 4.4 4.5 10.8 4.5 4.4 4.4 4.3 weight maximumlayer Å 1490 1290 860 350 210 1430 1450 1460 1490 1480 thickness averagelayer thickness Å 183 112 75 51 35 81 105 115 241 118 the number ofdispersing /wt % 51 69 93 108 121 56 68 64 41 56 particles 100 μ2 aspectratio 65 78 123 190 210 69 72 78 51 70 [R100] % 52 44 33 21 15 35 54 5650 57 [R200] % 37 27 18 9 6 20 38 40 36 41 [R300] % 30 19 11 6 3 12 3132 29 34 (*1) amount of silane-treated foliated phyllosilicate: amountof silane-treated foliated phyllosilicate contained in a glycoldispersion medium and BHET dispersion medium based on a resin (*2)PET/EG Polyester having a low polymerization degree was used, which wasobtained by depolymerizing PET with EG. (*3) PBT/1.4-BD Polyester havinga low polymerization degree was used, which was obtained bydepolymerizing PBT with 1.4-BD.

TABLE 4 example 1 2 3 4 5 6 7 8 9 10 flexural strength MPa 150 144 138130 130 155 148 139 142 120 flexural modulus MPa 6050 5850 5600 53905350 7100 5830 5750 5800 3950 deflection ° C. 220 212 205 198 195 235223 205 215 193 temperature under load warpage mm <0.1 <0.1 <0.1 0.1 0.1<0.1 <0.1 <0.1 0.1 0.2 coefficient MD 10⁻⁵/ 5.62 5.63 5.98 6.23 6.334.12 5.98 5.78 6.31 5.89 of linear direction ° C. expansion TD 10⁻⁵/5.63 5.65 6.05 6.35 6.46 4.12 6.06 5.81 6.46 5.91 direction ° C. MD/TD1.00 1.00 0.99 0.98 0.98 1.00 0.99 0.99 0.98 1.00 shrinkage MD % 1.3101.315 1.330 1.358 1.362 1.205 1.315 1.320 1.314 1.180 ratio direction TD% 1.314 1.328 1.357 1.400 1.409 1.205 1.340 1.333 1.342 1.191 directionMD/TD 1.00 0.99 0.98 0.97 0.97 1.00 0.98 0.99 0.98 0.99 roughness at μm0.04 0.04 0.04 0.02 0.02 0.06 0.04 0.04 0.04 0.02 center line surface ∘∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ ∘ appearance

COMPARATIVE EXAMPLE 1

A polymerization apparatus having a scraper and equipped with atwin-screw stirring blade having high shearing ability and adistillation tube was chaged with 2600 g of a dispersion system BHET-a(in a molten state at 120 to 140° C.), 6.0 g of a stabilizer AO60 and0.36 g of Sb₂O₃.

While the mixture was heated gradually 140° C. to 240° C., stirring wascontinued for about 3 hours in order to apply shear to the system.Subsequently, poly(ethylene terephthalate) (PET) was polymerized withstirring under reduced pressure (0.5 to 5.0 torr) at a polymerizationtemperature of 280° C. A logarithmic viscosity of the resin was 0.59(dl/g).

The resin was evaluated in the same manner as Example 1. Results areshown in Table 5.

COMPARATIVE EXAMPLE 2

Montmorillonite treated with organo-silanes was prepared by spraying 10g of A1120 to 100 g of montmorillonite with a spray and stirring for 1hour. The montmorillonite treated with organo-silanes had a basalspacing of 13 Å. FT-IR was measured after washing with THF to observeabsorption bands derived from a primary amino group, a secondary aminogroup and an ethylene group.

PET was depolymerized in the same manner as Example 1 under dry nitrogenstream (after depolymerization, a sampled mixture had a logarithmicviscosity of 0.11 (dl/g)). And 100 g of the montmorillonite treated withorgano-silanes was continuously added under stirring with an H-shapedstirring blade.

Subsequently, the system was heated to 280° C., and the pressure wasreduced (0.5 to 5.0 torr) to polymerize in melt condensation. Thepolyester resin compositions obtained in the above-mentioned manner wereevaluated. The results are shown in Table 5.

COMPARATIVE EXAMPLE 3

A polyester resin composition was prepared in the same manner as inComparative Example 2 except for using montmorillonite (100 g) in placeof the montmorillonite treated with organo-silanes to evaluate it. Theresults are given in Table 5.

REFERENTIAL EXAMPLE 1

An autoclave equipped with a distillation tube and a rectifying columnwas chaged with 2500 g of dimethyl terephthalate, 1600 g of EG, 7.5 g ofAO60 and 0.60 g of titanium tetrabutoxide and the mixture was stirred ata reaction temperature of about 190° C. for about 3 hours totransesterify dimethyl tetraphthalate and EG. Subsequently, therectifying column was detached, 0.6 g of antimony trioxide was added topolymerize in melt condensation at a reaction temperature of 270 to 280°C. under reduced pressure (0.8 to 5.0 torr). The obtained PET resin wasevaluated. The results are shown in Table 5.

REFERENTIAL EXAMPLE 2

An autoclave equipped with a distillation tube and a rectifying columnwas chaged with 2170 g of dimethyl terephthalate, 2000 g of 1,4-BD, 7.5g of AO60 and 0.65 g of titanium tetrabutoxide with stirring at areaction temperature of about 190° C. for about 3 hours to transesterifydimethyl terephthalate and 1,4-BD. Subsequently, the rectifying columnwas detached and melt condensation polymerization was conducted at areaction temperature of 250 to 270° C. under reduced pressure (0.8 to5.0 torr). The obtained PBT resin was evaluated. The results are shownin Table 5.

TABLE 5 comparative example referential example example 1 2 3 1 2 resinPET PET PET PET PBT swellable phyllosilicate silane-treatedmontmorillonite montmorillonite — foliated treated with silanephyllosilicate-a logarithmic viscosity of resin dl/g 0.62 0.63 0.63 0.620.83 amount of filler (*1) parts by 4.8 4.8 4.8 0 0 weight ash content %by weight 4.6 4.5 4.5 0 0 maximum layer Å 83 1,000,000 900,000 thickness(*2) average layer thickness (*3) Å 19 33300 31600 the number ofdispersing /wt % 145 1 1 particles 100 μ2 aspect ratio (*4) 240 1.5 1.5[R100] % 0 0 0 [R200] % 0 0 0 [R300] % 0 0 0 flexural strength MPa 118106 103 104 85 flexural modulus MPa 5050 3110 3190 2970 2610 deflectiontemperature ° C. 190 145 150 140 160 under load warpage mm 0.5impossible to impossible to impossible to 10.9 mold mold moldcoefficient MD direction 10⁻⁵/° C. 6.95 7.40 7.39 7.41 6.89 of linear TDdirection 10⁻⁵/° C. 8.24 12.16 12.18 12.22 14.23 expansion MD/TD 0.840.61 0.61 0.61 0.48 shrinkage MD direction % 1.350 impossible toimpossible to impossible to 1.315 ratio measure measure measure TDdirection % 1.460 impossible to impossible to impossible to 1.410measure measure measure MD/TD 0.92 — — — 0.93 roughness at center μm0.02 0.822 0.806 0.02 0.02 line surface appearance ∘ ∘ Δ Δ ∘ ∘ (* 1)amount of filler: amount of silane-treated foliated phyllosilicate,montmorillonite treated with silane, and montmorillonite based on aresin (*2) The value was defined as a number average of shorter diameterof dispersing particles, since particles were not dispersed in a platestate. (*3) The value was defined as a maximum value of shorter diameterof dispersing particles, since particles were not dispersed in a platestate. (*4) The value was defined as a ratio of longer diameter toshorter diameter of dispersing particles, since particles were notdispersed in a plate state.

INDUSTRIAL APPLICABILITY

According to the present invention, resin molded articles havingsufficiently improved flexural properties, deflection temperature underload and dimension stability (reduction in warpage and anisotropy incoefficient of linear expansion and heat shrinkage ratio) and excellentsurface appearance can be obtained by making a thermoplastic polyesterresin contain at least 10% of a silane-treated foliated phyllosilicatehaving a layer thickness of substantially at most 2000 Å and having alayer thickness of more than 100 Å and at most 2000 Å, resin moldedarticles having fully improved bending characteristics, deflectiontemperature under load and dimension stability (reduction in warpage,coefficient of linear expansion and heat shrinkage) and having goodsurface appearance can be obtained

As previously mentioned in detail, if a silane-treated foliatedphyllosilicate has a layer thickness of substantially at most 2000 Å,its incorporation into a thermoplastic polyester resin does not affectsurface appearance of molded articles or the like. Moreover, since it isdifficult to warp when it has a layer thickness of more than 100 Å andat most 2000 Å, a reinforcing effect on resin, an effect on dimensionstability or the like can be efficiently achieved.

The polyester resin composition of the present invention can beobtained, for example, by the preparing process of the presentinvention, namely, a preparing process comprising a silane-treatedfoliated phyllosilicate preparing step (A) in which a basal spacing of aswellable phyllosilicate is expanded in a dispersion medium andthereafter an organo-silane is introduced to obtain a silane-treatedfoliated phyllosilicate; a dispersion system preparing step (B) in whicha glycol dispersion system containing the silane-treated foliatedphyllosilicate and glycols is prepared; a mixture preparing step (C) inwhich the glycol dispersion system is added to a polyester unit and/or apolyester having a low polymerization degree in a molten state to obtaina mixture; and a molecular weight increasing step (D) in which amolecular weight of the polyester unit and/or the polyester having a lowpolymerization degree in the mixture is increased by a condensationpolymerization reaction.

What is claimed is:
 1. A polyester resin composition comprising athermoplastic polyester resin and a silane-treated foliatedphyllosilicate, wherein the silane-treated foliated phyllosilicate isprepared by introducing an organo-silane represented by the followinggeneral formula (I): Y_(n)SiX_(4−n)  (1) wherein n denotes an integer of0 to 3, Y denotes a hydrocarbon group having 1 to 25 carbon atoms, Xdenotes a hydrolyzable group or a hydroxyl group, n units of Y or (4−n)units of X may, respectively, be the same or different if n or (4−n) isat least 2, into a swellable phyllosilicate, and wherein the maximumlayer thickness of the silane-treated foliated phyllosilicate in thepolyester resin composition is more than 200 Å and up to 1,800 Å;wherein said hydrocarbon group optionally comprises at least one of thefollowing: an ester bond, an ether bond, an epoxy group, an amino group,a carboxyl group, a carbonyl group, an amide group, a mercapto group, asulfonyl bond, a sulfinyl bond, a nitro group, a nitroso group, anitrile group, a halogen atom, and a hydroxyl group; and wherein thedispersing particle number [N] of the silane-treated foliatedphyllosilicate particles present in a 100 m² area of the polyester resincomposition is at least 30 based on unit proportion.
 2. The polyesterresin composition of claim 1, wherein the maximum layer thickness of thesilane-treated foliated phyllosilicate in the polyester resincomposition is 300 Å to 1500 Å.
 3. The polyester resin composition ofclaim 1, wherein the average layer thickness of the silane-treatedfoliated phyllosilicate in the polyester resin composition is at least20 Å and at most 500 Å.
 4. The polyester resin composition of claim 1,wherein the average layer thickness of the silane-treated foliatedphyllosilicate in the polyester resin composition is more than 50 Å andat most 300 Å.
 5. The polyester resin composition of claim 1, wherein anaverage aspect ratio (layer length/layer thickness ratio) of thesilane-treated foliated phyllosilicate in the polyester resincomposition is 10 to
 300. 6. The polyester resin composition of claim 1,wherein a proportion [100] of the number of silane-treated foliatedphyllosilicates having layer thickness larger than 100 Å to the totalnumber of the silane-treated foliated phyllosilicate is at least 10%. 7.The polyester resin composition of claim 1, wherein the [100] value isat least 30%.
 8. The polyester resin composition of claim 1, wherein the[100] value is at least 50%.
 9. The polyester resin composition of claim6, wherein a proportion [R200] of the number of the silane-treatedfoliated phyllosilicates having layer thickness larger than 200 Å to thetotal number of the silane-treated foliated phyllosilicates is at least0.3×[100] .
 10. The polyester resin composition of claim 6, wherein the[R200] value is at least 0.7×[100].
 11. The polyester resin compositionof claim 6, wherein a proportion [R300] value of the number ofsilane-treated foliated phyllosilicates having layer thickness largerthan 300 Å to the total number of the silane-treated foliatedphyllosilicates is at least 0.4×[R200].
 12. The polyester resincomposition of claim 9 wherein the [R300] value is at least 0.8×[R200].13. A process for preparing a polyester resin composition comprising athermoplastic polyester resin and a silane-treated foliatedphyllosilicate, which comprises (A) a step of preparing a silane-treatedfoliated phyllosilicate by introducing an organo-silane represented bythe following general formula (I): Y_(n)SiX_(4−n)  (I) wherein n denotesan integer of 0 to 3, Y denotes a hydrocarbon group having 1 to 25carbon atoms, X denotes a hydrolyzable group or a hydroxyl group, nunits of Y or (4−n) units of X may, respectively, be the same ordifferent if n or (4−n) is at least 2, into a swellable phyllosilicate,(B) a step of preparing a dispersion system by mixing the silane-treatedfoliated phyllosilicate and glycols, (C) a step of preparing a mixtureby adding the dispersion system to a molten polyester unit and/orpolyester with a low molecular weight, and (D) a step of increasing amolecular weight of the polyester unit and/or the polyester with a lowmolecular weight in the above mixture by condensation polymerization,wherein the maximum layer thickness of the silane-treated foliatedphyllosilicate is greater than 200 Å and up to 1,800 Å.
 14. The processfor preparing a polyester resin composition of claim 13, wherein, in thestep (A), the silane-treated foliated phyllosilicate is obtained byadding the organo-silane after enlarging a basal spacing of theswellable phyllosilicate in a dispersion medium, and thereby a basalspacing of the silane-treated foliated phyllosilicate becomes largerthan the initial basal spacing of the swellable phyllosilicate by theintroduced organo-silane.
 15. The process for preparing a polyesterresin composition of claim 13, wherein an basal spacing of thesilane-treated foliated phyllosilicate dispersing in the dispersionsystem obtained in the step (B) is at least three times larger than theinitial basal spacing of the swellable phyllosilicate.
 16. The processfor preparing a polyester resin composition of claim 13, wherein alogarithmic viscosity of the polyester unit and/or the polyester with alow molecular weight is at least 0.001 dl/g to less than 0.4 dl/g. 17.The process for preparing a polyester resin composition of claim 13,wherein the polyester unit and/or the polyester with a low molecularweight is obtained by depolymerizing a polyester resin material withglycols.